Hydrazine nitroform and method of preparation



United States Patent Office 393781594 Patented Apr. 16, 1%68 reaction, the reaction mixture is poured into an excess 3,378,594 of a nonsolvent, such as carbon tetrachloride or hexane,

g gg gg gfig gg METHGD and the yellow precipitate which forms is recovered by filtration, or other methods, and washed with additional 32; 3555335352 353 52 fggggggg si bggiggig 5 carbon tetrachloride before it is dried. Other organic N0 Drawing Filed Aug 3 1960 Sex. Nm 47,322 solvents which may be used in this embodiment are C 31 m (CL 260 644) to C straight and branched chain (ox-o) aliphatic monohydric or polyhydric alcohols, such as methanol, isooctyl The present invention relates to hydrazine mononitroalcohol, ethylene glycol, tridecyl alcohol, and cyclic form, a new compound, and the preparation thereof for 10 aromatic alcohols, such as phenol, cresols, etc.; ketones, use in rocket propellants. such as acetone, methyl ethyl ketone, methyl isobutyl Considerable effort has been expended in the search ketone, cyclohexanone, etc.; and aliphatic polar solvents, for high energy solid oxygen oxidizers that are useful such as dimethyl sulfoxide and dimethyl formamide. The in rocket propellant formulations. To be of practical value preferred diluents are water and the lower molecular these oxidizers should be dense, heat stable and relatively weight primary aliphatic alcohols, particularly methanol. shock insensitive both alone and when mixed with other Where water is used as the diluent, the reaction product ingredients, in addition to being sources of large amounts can be recovered by simply evaporating the water from of available oxygen. It has now been found that hythe reaction mixture at atmospheric or reduced pressures. d-r-azine mononitroform has the above-mentioned prop- Because of the salt-like characteristic of the reaction erties. It was surprising to find that hydrazine mono- 2 product, nonpol-ar liquids including C to C aliphatic nitroform is thermally stable since most nitroform comand aromatic hydrocarbons, perhalocarbons and ethers pounds decompose rapidly at room temperature or below. are excellent precipitating agents. Among the suitable pre- The novel hydrazine compound shows no signs of decipitating agents are benzene, diethyl ether and carbon composition even after aging months at room temperatetrachloride. Carbon tetrachloride is preferred mainly ture, and it does not decompose even when heated to for safety reasons. 77 C. and kept there for long periods of time, e.g. 40 Alternatively, the diluent is a nonsolvent liquid, such hours. Some decomposition is evident, however, when it as diethyl ether, and the solid reaction product is reis heated to about 110 C. Moreover it is relatively shock covered by filtration after mixing the two reactants. Since insensitive (12 kg. inch) and its sensitivity is not inat least one of the starting materials is insoluble in solcreased by mixing it with powdered aluminum, Thi fact vents of this type, this is a less satisfactory method beis of considerable importance in View of the fact that other cause the product may be contaminated with impurities equally good oxygen sources have failed to become operaand unreacted material unless it is further purified. tional because of their extreme sensitivity in aluminized Among the useful nonsolvents are lower molecular weight formulations. The nitroform compound, which can be others, such as dioxan, diisopropyl and ethyl isopropyl called hydraziniurn nitroformate, may be described by the th following formula: Any inert diluent can be used provided it is present in a sufiicient quantity to facilitate mixing the reactants NH2NH2 HC(NO2)3 during the reaction. For instance, about 2 to 20 volumes It has a density of 1.86 and its heat of formation is about of diluent, e.g. methanol, can be separately admixed with 11 K. cal. mol. each volume of hydrazine and nitroform and the diluted Hyd razine mononitroform can be prepared by mixing reactants may be added in any order to the reaction vessel equimolar amounts of hydrazine (anhydrous or hywith stirring. It will be noted that the color of the reaction drated) and nitroform at about 0 to C. and submixture changes from a light yellow to a rich gold as stantially atmospheric pressure. The reaction commences the reaction proceeds. immediately upon mixing the two reactants in the proper 45 The solid yellow crystalline product obtained by any proportions and is usually complete as soon as all of of the foregoing processes is useful as a monopropellant each reactant has been introduced in the reaction zone and an explosive. It can also be mixed with about 10 provided the reaction mixture is rapidly agitated with a to 40 vol. percent binder and solid metal fuels such as stirrer or other mixing means. Longer periods of time, aluminum, beryllium, lithium, boron and other solid Lo. 5 or 10 minutes, are necessary when the reaction mix- 0 oxidizers to make chemically balanced rocket propellants. ture is not well agitated. By using equimolar amounts The following is a comparison of this compound with quantitative yields of product are obtained and little or other known oxygen-containing oxidizers in chemically no purification is necessary. balanced formulas:

COMPARISON OF OXYGEN OXIDIZERS IN ALUMINIZED SYSTEMS 1 NPU=Nitropolyurethaue 2 ISP Specific impulse.

3 RBV-CM= Relative boost velocity-constant mass.

4 RBV-CV= Relative boost velocity-constant volume.

In a preferred embodiment of the invention, the re- The data show that the hydrazine salt is an outstanding action is effected under ambient conditions for from a oxidizer in relation to other oxidizers in the optimum few seconds to 2 or 3 minutes in the presence of an formulations. inert solvent, such as methanol. The term inert is in- Aside from the foregoing uses, hydrazine mononitrotended to mean that the diluent should not interfere with form may be used in situ as a convenient source of nitrothe reaction in any Way, although it may catalyse it if form, a normally unstable chemical. Unlike other nitroit has the capacity to do so. Upon completion of the formate salts, the hydrazine compound can be stored for long periods of time at ambient temperature. Moreover, the nitroform portion of the salt can be released by reacting it with an appropriate reagent. For example, trinitroethanol, itself a valuable intermediate in the synthesis of certain high energy propellants, may be prepared by reacting aqueous formaldehyde with a solution of hydrazine nitroform in water.

The following examples illustrate the invention:

EXAMPLE 1 Nitroform (0.31 g.) dissolved in 20 ml. of diethyl ether was added dropwise to a rapidly stirred Suspension of 64 mg. of anhydrous hydrazine in 2 ml. of diethyl ether at C. The mixture was then stirred for 15 minutes. Evaporation of the ether gave a yellow crystalline solid. The salt was quite pure. It can be recrystallized from methanol-carbon tetrachloride mixtures, if desired. The calculated nitrogen for hydrazine mononitroform is 38.3%. A nitrogen analysis showed it contained 38.7% nitrogen. The A maximum of the ultraviolet spectrum was 348 m and e equaled 1.5 10- L mole cmf The product has a density of 1.86 g./cc. (liquid displacement method) and was soluble in methanol, water and anhydrous hydrazine. Its autoignition was 5 seconds at 165 C. and showed no decomposition after 7 days at ambient temperature.

EXAMPLE 2 Anhydrous hydrazine (0.2 g.) in 2.0 ml. methanol was added to a rapidly stirred solution of nitroform (1.1 g.) in 10 ml. of methanol in a 50 ml. beaker over a period of a few seconds at ambient temperature and atmospheric pressure. The mixture was then stirred for a few minutes. A golden colored solution was obtained. The liquid reaction mixture was poured into a 500 ml. beaker containing a large excess (200 ml.) of rapidly stirred carbon tetrachloride at room temperature and the yellow precipitate that formed was filtered and washed with pure carbon tetrachloride. The product was dried in a vacuum desiccator for 24 hours at room temperature. It was analyzed and found to contain 38.4% nitrogen.

EXAMPLE 3 .454 g. of nitroform was dissolved in 1.0 ml. of water. To this solution was added dropwise 0.10 cc. of hydrazine hydrate dissolved in 1.0 cc. of water. Evaporation to dryness produced a yellow crystalline hydrazine mononitroform.

Resort may be had to various modifications and variations of the process without departing from the scope of the present claims. For instance, an inert gas, such as nitrogen, may be used as the atmosphere of the reaction or excesses of nitroform or hydrazine may be employed. Also pressure, e.g. 10 p.s.i.g., can be utilized especially when low boiling diluents are used. However, the process can be economically and easily carried out in an open glass vessel at room temperature and atmospheric pressure.

What is claimed is:

1. Process for preparing hydrazine mononitroform which comprises reacting hydrazine with nitroform in an equimolar proportion in an inert organic liquid diluent, precipitating the resulting formed hydrazine mononitroform from the diluent in a nonpolar organic liquid nonsolvent for the hydrazine mononitroform, and recovering the precipitated hydrazine mononitroform.

'2. Process for preparing hydrazine mononitroform which comprises reacting anhydrous hydrazine with nitroform in equimolar amounts in the presence of an inert organic solvent at 0 to 50 C. for a sufiicient period of time to form hydrazine nitroform which is dissolved by said solvent, admixing the reaction mixture containing the formed hydrazine mononitroform with an excess of a nonpolar organic liquid which is a non-solvent for the hydrazine mononitroform to precipitate the hydrazine mononitroform and recovering the precipitate.

3. Process for preparing high purity hydrazine mononitroform which comprises admixing a methanol solution of anhydrous hydrazine with a methanol solution of nitroform, reacting the hydrazine with an equimolar proportion of the nitroform in the resulting reaction mixture, admixing with the resulting liquid reaction mixture containing hydrazine mononitroform a sufficient amount of a nonpolar organic liquid non-solvent.to precipitate the mononitroform from the methanol solution, and recovering the thus precipitated hydrazine mononitroform.

'4. Process for preparing high-purity hydrazine mononitroform which comprises, dissolving hydrazine mononitroform containing impurities in an inert organic liquid solvent to form a solution of the hydrazine mononitroform in the solvent, and precipitating the hydrazine mononitroform from said solution by adding to the solution a nonpolar organic liquid non-solvent hydrazine mononitroform salt, and recovering the thus precipitated hydrazine mononitroform of high purity.

5. High-purity hydrazine mononitroform of increased stability consisting of hydrazine mononitroform washed with and wet with carbon tetrachloride.

6. Process for preparing hydrazine mononitroform which comprises reacting anhydrous hydrazine with nitroform in equimolar amounts in the presence of methanol as solvent at 0 to 50 C. for a sufficient period of time to form hydrazine nitroform which is dissolved by said solvent, admixing the reaction mixture containing the formed hydrazine mononitroform with an excess of.carbon tetrachloride which is a nonsolvent for the hydrazine mononitroform to precipitate the hydrazine mononitroform and recovering the precipitate.

7. In the process of preparing hydrazine mononitroform by reacting hydrazine with nitroform to form hydrazine mononitroform which contains impurities, the improvement which comprises washing the hydrazine nitroform salt with a nonpolar organic liquid which is a nonsolvent for the hydrazine nitroform salt.

8. In the improvement defined by claim 7, said nonpolar organic liquid being selected from the group consisting of C to C aliphatic and aromatic hydrocarbons, perhalocarbons, and ethers.

9. In a process for preparing hydrazine mononitroform which is formed by reacting hydrazine with nitroform to obtain hydrazine nitroform salt, the improvement which comprises dissolving and recrystallizing said salt in a mixture of an alcohol solvent for the salt and a nolnpolar organic liquid which is a nonsolvent for said sa t.

10. In the improvement defined in claim 9, the mixture of the alcohol and the nonpolar organic liquid being methanol and carbon tetrachloride.

References Cited UNITED STATES PATENTS 2,615,920 10/1952 Bahner 260583 2,786,078 3/1957 Sawer 260583 2,930,683 3/1960 Adelrnan 520.5 2,966,403 12/1960 Weil 520.5 2,963,507 12/1960 Rudner et al 260583 3,140,317 7/1964 Groves 260644 3,213,609 10/1965 Johnston et al. 149--36 X 3,297,747 1/1967 Thornton 260644 X OTHER REFERENCES Weissberger: Technique of Organic Chemistry, vol. III, second edition (1956), Part 1, Separation and Purification. Published by Interscience Publishers Inc., N.Y., pp. 475- 479.

CARL D. QUARFORTH, Primary Examiner.

LEON D. ROSDOL, OSCAR R. VERTIZ, Examiners.

B. R. PADGETT, J. W. WHISLER, L. A. SEBASTIAN,

Assistant Examiners. 

1. PROCESS FOR PREPARING HYDRAZINE MONNITROFORM WHICH COMPRISES REACTING HYDRAZINE WITH NITROFORM IN AN EQUIMOLAR PROPORTION IN AN INERT ORGANIC LIQUID DILUENT, PRECIPITATING THE RESULTING FORMED HYDRAZINE MONONITROFORM FROM THE DILUENT IN A NONPOLAR ORGANIC LIQUID NONSOLVENT FOR THE HYDRAZINE MONONITROFORM, AND RECOVERING THE PRECIPITATED HYDRAZINE MONONITROFORM.
 5. HIGH-PURITY HYDRAZINE MONONITROFORM OF INCREASED STABILITY CONSISTING OF HYDRAZINE MONONITROFORM WASHED WITH AND WET WITH CARBON TETRACHLORIDE. 